1 files changed, 115 insertions, 0 deletions
diff --git a/7/solution.py b/7/solution.py
new file mode 100644
index 0000000..77a1391
--- /dev/null
+++ b/7/solution.py
@@ -0,0 +1,115 @@
+from abc import abstractmethod
+
+class U16:
+    def __init__(self, value: int):
+        self.value = value & 0xffff
+    def __invert__(self):
+        return U16(~self.value)
+    def __and__(self, other):
+        return U16(self.value & other.value)
+    def __or__(self, other):
+        return U16(self.value | other.value)
+    def __rshift__(self, other):
+        return U16(self.value >> other.value)
+    def __lshift__(self, other):
+        return U16(self.value << other.value)
+    def __str__(self):
+        return str(self.value)
+
+class Node:
+    _value: U16 = None
+    @property
+    def value(self) -> U16:
+        if not self._value:
+            self._value = self.eval()
+        return self._value
+    def eval(self, net: dict[Node]) -> U16:
+        return self.eval()
+    @absrtactmethod
+    def eval(self) -> U16:
+        pass
+
+class Reference(Node):
+    def __init__(self, name: str):
+        self.name = name
+    def eval(self, net: dict[Node]) -> U16:
+        return net[self.name].value
+
+class Constant(Node):
+    def __init__(self, value):
+        self._value = value
+
+class BinaryOp(Node):
+    def __init__(self, left, right):
+        self.left = left
+        self.right = right
+
+class And(BinaryOp):
+    def eval(self) -> U16:
+        return self.left.value & self.right.value
+
+class Or(BinaryOp):
+    def eval(self) -> U16:
+        return self.left.value | self.right.value
+
+class LShift(BinaryOp):
+    def eval(self) -> U16:
+        return self.left.value << self.right.value
+
+class RShift(BinaryOp):
+    def eval(self) -> U16:
+        return self.left.value >> self.right.value
+
+class Not(Node):
+    def __init__(self, node):
+        self.node = node
+    def eval(self):
+        return ~self.node.value
+
+def parse_expr(net: dict[Node], expr: str) -> Node:
+    parts = expr.split(' ')
+    if len(parts) == 3:
+        lhs = parse_expr(net, parts[0])
+        rhs = parse_expr(net, parts[2])
+        if parts[1] == 'AND':
+            return And(lhs, rhs)
+        elif parts[1] == 'OR':
+            return Or(lhs, rhs)
+        elif parts[1] == 'LSHIFT':
+            return LShift(lhs, rhs)
+        elif parts[1] == 'RSHIFT':
+            return RShift(lhs, rhs)
+    elif len(parts) == 2:
+        if parts[0] == 'NOT':
+            return Not(parse_expr(net, parts[1]))
+    elif len(parts) == 1:
+        if expr.isnumeric():
+            return Constant(U16(int(expr)))
+        if expr.isalpha():
+            return Reference(net, expr)
+    raise ValueError(expr)
+
+def parse_conn(net: dict[Node], conn: str) -> tuple[str, Node]:
+    expr, target = conn.split(" -> ")
+    return target, parse_expr(net, expr)
+
+def part1(inp: list[str]) -> int:
+    net = dict()
+    for conn in inp:
+        target, node = parse_conn(net, conn)
+        net[target] = node
+    return net['a'].value
+
+def part2(inp: list[str]) -> int:
+    net = dict()
+    for conn in inp:
+        target, node = parse_conn(net, conn)
+        net[target] = node
+    net['b'] = Constant(part1(inp))
+    return net['a'].value
+
+if __name__ == '__main__':
+    with open('input') as f:
+        inp = [line.strip() for line in f]
+    print(part1(inp))
+    print(part2(inp))
+\ No newline at end of file